Various materials for travelled surfaces (or portions thereof) for pedestrian or light vehicle traffic are known. For example, a travelled surface such an outdoor patio or sidewalk may have a segmental pavement system which includes “hardscaping” elements (e.g., discrete pavement stones). The pavement stones, which are usually somewhat irregularly shaped, are spaced apart from each other on a base, resulting in gaps between the stones. In the prior art, these gaps are filled with a variety of materials to approximately the height of adjacent pavement stones, so that the travelled surface is easier to travel over. The material placed in the gaps (often referred to as “jointing material”) also assists in holding the pavement stones in place. Accordingly, where the segmental paving system is used in the travelled surface, jointing material positioned in the gaps between the hardscaping elements provides at least a portion of the travelled surface.
In the prior art, an untreated aggregate is often used as the jointing material, i.e., an aggregate without any additives included therein. Typically, the aggregate is manufactured, i.e., a product of processes which are well known in the art. However, any suitably sized aggregate may be used. The type of aggregate which is used to fill the gaps in the prior art is sand or crushed stone of generally smaller diameter, usually depending on the widths of the gaps to be filled.
The untreated aggregate is an unsatisfactory jointing material for a number of reasons. For instance, the untreated aggregate tends to erode relatively quickly. Also, the untreated aggregate provides a number of crevices and holes in which germination of seeds often occurs, especially after some erosion has taken place. This is undesirable both for esthetic reasons and because plants may obstruct travel over the travelled surface, e.g., if they are sufficiently large.
One possible solution to the problems resulting from using untreated aggregate as the jointing material is to use concrete instead, because concrete would resist erosion better. However, when concrete is used as jointing material, it tends to crack due to movement of the base, and/or movement of the pavement stones relative to each other. Such movement can occur for a number of reasons, such as heaving of the base due to its freezing and thawing, or subsidence of parts of the base at different rates, for example. Germination of seeds can take place in the cracks resulting from the movement.
From the foregoing, it can be seen that there is a need for a jointing material which resists erosion well but is also flexible and resilient, so that movement of pavement stones relative to each other and movement in the base can be accommodated.
Many travelled surfaces do not include hardscaping elements. In the prior art, these travelled surfaces (which are usually trails or paths) can be made of different materials, such as untreated aggregate, asphalt, or wood chips. However, each of these materials has one or more disadvantages. For instance, untreated aggregate is relatively easily eroded, and plants can germinate in the aggregate. Asphalt is relatively expensive, and tends to crack over time due to uneven settlement of the base or frost heaving. Wood chips do not provide a cohesive surface, and therefore are somewhat inconvenient for some applications.
In the prior art, aggregate has been mixed with psyllium alone. However, in this context, the psyllium tends to decay and/or to be leached out by rainwater. Also, psyllium, when used alone in aggregate, does not discourage plant growth. Therefore, the use of psyllium alone, with aggregate, does not provide satisfactory results in a travelled surface.
Accordingly, there is a need for an improved material for providing at least a portion of a travelled surface.